<style>
  .folder {}

  .folder[folded] {
    overflow-y: hidden;
  }

  .folder-legend {
    cursor: default;
  }

  .folder-arrow {
    font-family: 'Courier New', Courier, monospace;
    font-size: 1.5em;
    font-weight: 900;
    cursor: default;
  }
</style>

<dom>
  <fieldset class="folder">
    <legend class="folder-legend" @click="onToggle"><span $="lbTitle">Title</span><span class="folder-arrow"
        $="lbArrow">-</span>
    </legend>
  </fieldset>
</dom>